1. Field of the Invention
The present invention generally relates to a current source circuit using a depletion-type metal oxide semiconductor (MOS), and a delay circuit and an oscillating circuit using the depletion-type metal oxide semiconductor (MOS).
2. Description of the Related Art
A depletion-type metal oxide semiconductor (MOS) has various usages such as a current source circuit.
FIG. 26A is an example current source circuit using a depletion-type metal oxide semiconductor. Referring to FIG. 26A, a drain of the depletion-type N-channel MOS transistor 1 is connected to a positive pole, and a negative pole of a direct-current power source 2 is grounded. The source and the gate of the MOS transistor 1 are mutually connected and further connected to a terminal 3. The current source circuit applies a constant electric current to the terminal 3.
Referring to FIG. 26B, the drain of an N-channel MOS transistor 1 is connected to a terminal 4. The source and the gate of the MOS transistor 1 are mutually connected and further grounded. The current source circuit applies a constant electric current to the terminal 4.
There is a known technique that a resistor and an enhancement MOS transistor are used to compensate for a current-temperature property of a depletion-type N-channel MOS transistor (see Patent Document 1).
In the example circuits illustrated in FIG. 26A and FIG. 26B, the depletion-type N-channel MOS transistor has a positive temperature property in which the drain current increases when the temperature increases. FIG. 27 illustrates a drain-temperature property of the depletion-type MOS transistor. As illustrated, since the current source circuit using the example depletion-type MOS transistor illustrated in FIG. 26A and FIG. 26B has a positive temperature property, it is necessary to compensate for the temperature property in order to flatten the temperature property of the current source circuit.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-236521